How to work with Metz 40 mz2 and Contax 645 combo properly?

[paul utkin]

Hi,

 

I never used Metz products before so this flash was the first one

that I`ve got.

 

I spent yesterday�s evening torturing this flash in all available

modes and found out that 'A' mode typically is more consistent and

reliable than 'TTL' with my camera. Is it a common thing?

 

I tested it in quite simple way - left my flashmeter hanging next to

background and tested power of flash output against medium gray

subject with black/white and mixed backdrops on different apertures.

 

In some cases in TTL mode with apertures above 8 flash didn`t report

the success even if flashmeter showed the opposite. It also appears

that camera`s meter is way too unpredictable - overexpose shift

amount against black backdrop wasn`t the same with underexpose shift

against white - it was something like 8 with black and 2.8+1/3 with

white with 5.6 aperture on camera. I find it kinda strange.

 

I tried to shoot against 50/50 black/white background and got

constant underexpose with ttl all the time. 'A' mode gave me correct

exposure in the same situation, as well as pretty stable +1 -1 stop

shifts against white/black backdrops - just as it supposed to be.

 

Does it mean that sensor in my camera is not OK and has to be

readjusted? If so - is it possible to do it at home anyhow?

Is anything wrong here at all or is it a common thing for this

camera/flash combo? Can anybody explain in more details the logic of

Contax`s TTL flash metering?

 

I just find it to be pretty difficult to predict the appropriate

flash compensation amount in field situation. Is it a

common/recommended practice to use Metz`s 'A' mode on location

instead of 'TTL'? Is it reliable enough to be used on location?

 

PS. I forgot to mention - I used sca3802 adapter with this 40 mz2.

[jhbeckman]

Just out of curiosity -- did you have film in the camera? I cannot remember how the C645 meters flash, but many cameras meter off the film. If you are trying to measure TTL flashes w/out film in the camera, this may be why you're getting odd readings.

 

By contrast, the A setting would not be affected by the absence of film

[paul utkin]

Hmm...

 

It`s a valid point. I do not know if it was the reason.

 

Well, darkslide was inserted and I tried to do usual preflash metering in the usual way it can be done. I believe camera didn`t cock shutter during this action so darkslide and film should not be able to affect the results. Am I right?

[chris_henry1]

TTL metering off the shutter curtain, right. The shutter is always cocked as

long as the camera has been turned on and the camera has advanced the

film to the next available frame.

[picturesque]

Besides maybe needing film in the camera to test TTL, there are two other things to consider. Metz's website, under the FAQ section, says that your flash meter may not accurately measure flash if the flash is too short, resulting in apparent underexposure according to the meter, but not actually. Also, using print film, not slide film, I have found that Metz flashes do better set about 2/3 to a stop over in the A setting, meaning, if your film is ASA 400, I would set the flash to ASA 200 or 250, forcing it to overexpose. In TTL, I found it depends on the camera's TTL method. I have the 60 CT-4 and the 40 MZi.

[gary_ferguson1]

What's the result when measuring off a grey card? The Contax 645 uses spot metering for pre-flash measurement and this may have been confused with a 50:50 black and white background. Also, try testing with a dummy film of your usual type to match film reflectance.

 

I use the Contax 645 with a Metz 54 and get reliable and consistent results in TTL mode.